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# Porphyria cutanea tarda

The most common porphyria: blisters and fragile skin on the backs of the hands and the face, due to failure of a liver enzyme.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Skin](https://durgical.com/en/anatomy/skin/)
- [Liver](https://durgical.com/en/anatomy/liver/)

## In biochemistry

- [Heme synthesis: Step 5 · Uroporphyrinogen decarboxylase](https://durgical.com/en/biochemistry/pathways/heme-synthesis/#paso-5)
- [Uroporphyrinogen decarboxylase](https://durgical.com/en/biochemistry/enzymes/uroporphyrinogen-decarboxylase/)

## What it is

Chronic cutaneous porphyria caused by low uroporphyrinogen decarboxylase activity in the liver, which builds up photosensitising porphyrins in the skin.

## Who gets it

It is the most common porphyria worldwide; it appears in adults, more often in men. In Latin America it is linked mainly to alcohol, hepatitis C and HIV.

## Causes

- Type 1 (acquired, the majority): UROD inhibition in the liver
- Type 2 (familial): one mutated UROD allele plus triggers

## Risk factors

- Alcohol
- Hepatitis C and HIV
- Iron overload, HFE mutations
- Estrogens and smoking

## Pathophysiology

Iron and oxidative stress in the hepatocyte turn some uroporphyrinogen into uroporphomethene, which inhibits UROD. Uroporphyrin and highly carboxylated porphyrins build up; they reach the skin, absorb visible light and produce radicals that split the epidermis from the dermis.

## Symptoms and signs

- Blisters and erosions on the backs of the hands, forearms and face after sun exposure
- Fragile skin that tears with minor trauma
- Scars, milia and dark patches
- Excess hair on the cheeks and temples (hypertrichosis)
- Reddish or tea-coloured urine

## Red flags

- Jaundice or signs of cirrhosis
- A new liver nodule

## Diagnosis

**Clinical**
Blisters and fragility on sun-exposed [skin](https://durgical.com/en/anatomy/skin/) in an adult with alcohol use, hepatitis C or high iron; there are no abdominal attacks.

**Tests**
Markedly raised urine porphyrins dominated by uroporphyrin and heptacarboxylporphyrin; normal porphobilinogen; plasma porphyrins with a typical fluorescence peak; ferritin and transferrin saturation; hepatitis C, HIV and HFE testing.

**Imaging**
[Liver](https://durgical.com/en/anatomy/liver/) ultrasound to look for steatosis, cirrhosis or hepatocellular carcinoma.

## Treatment

**Procedure**
Regular phlebotomy to lower liver iron to a low-normal ferritin

**Medical**
Low-dose hydroxychloroquine regimen when phlebotomy is not possible

**Medical**
Antiviral treatment of hepatitis C, which often leads to remission

**Lifestyle**
Stopping alcohol, smoking and estrogens; protecting the skin from visible light and sun

## Complications

- Scarring and alopecia
- Cirrhosis
- Hepatocellular carcinoma

## Prognosis

With treatment lesions resolve within months; it can relapse if triggers return.

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme fails in porphyria cutanea tarda?

Liver uroporphyrinogen decarboxylase.

## Why does phlebotomy improve porphyria cutanea tarda?

It lowers liver iron, which drives formation of the UROD inhibitor.

## Which viral infection is often associated with porphyria cutanea tarda?

Hepatitis C (HIV as well).

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## Related conditions

- [Hereditary hemochromatosis](https://durgical.com/en/conditions/hereditary-hemochromatosis/)
- [Acute intermittent porphyria](https://durgical.com/en/conditions/acute-intermittent-porphyria/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [Hepatocellular carcinoma](https://durgical.com/en/conditions/hepatocellular-carcinoma/)
- [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Porphyria: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/porphyria/) (MedlinePlus, US National Library of Medicine, 2026); [UROD gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/urod/) (MedlinePlus, US National Library of Medicine, 2026); [Porphyrins urine test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003614.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Source: https://durgical.com/en/conditions/porphyria-cutanea-tarda/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/porphyria-cutanea-tarda/